Buck regulators are commonly used for changing the voltage or polarity of a power supply. Buck regulators typically employ two electronic switches (typically MOSFETs) in combination with an output inductor. The switches are alternately switched, thereby providing voltage pulses to the output inductor. The output inductor filters the pulse voltage to provide DC output voltage.
Isolated DC—DC converters are often implemented with self-driven synchronous rectifiers. Typically in this case, the synchronous rectifiers are driven with energy from a dedicated transformer winding. In a non-isolated DC—DC converter however, such as some bridge-buck circuits, no such winding is available. Nevertheless, a technique for self-driving synchronous rectifiers in a non-isolated converter could provide efficiency and cost advantages.